折半查找(迭代实现)

#include<iostream>
using namespace std;
const int list_size=10;
int binsearch(int list[],int searchnum,int left,int right);
int compare(int x,int y);
int main()
{
    int list[]={1,2,3,5,7,8,9,12,15,18};
    cout<<"输入要查找的数： ";
    int seanum;
    cin>>seanum;
    int suc=binsearch(list,seanum,0,list_size);
    if(suc==-1)
        cout<<"未查到数字"<<endl;
    else
        cout<<"已查找到数字"<<endl;
    return 0;
}
int binsearch(int list[],int searchnum,int left,int right)
{
    while(left<=right){
        int middle=(left+right)/2;
        switch(compare(list[middle],searchnum)){
        case 1:
            right=middle-1;
            break;
        case 0:
            return middle;
        case -1:
            left=middle+1;
            break;
        }
    }
    return -1;
}
int compare(int x,int y)
{
    if(x==y)
        return 0;
    else if(x<y)
        return -1;
    else
        return 1;
}